The normal functions of an organism gradually decline with ageing and the exact mechanism are not totally understood. One consensus upon almost all specialists is that mitochondria are involved in the ageing process (Payne, B. A. I. and P. F. Chinnery. 2015 “Mitochondrial dysfunction in aging: Much progress but many unresolved questions.” Biochimica et Biophysica Acta 1847; 11: 1347-1353).